The present invention relates to passive safety belt arrangements for vehicles, e.g. passenger automobiles, and, more particularly, to devices in which the belt is shifted along a guide in the frame of the vehicle.
In German Offenlegungsschrift No. 27 24 402 there is shown a passive restraint system in which one end of a safety belt is articulately coupled to a member that slides in a guide fastened to the frame of the vehicle. The guide is located in the region of a door opening positioned in the vicinity of the vehicle seat. Shifting of the articulation member takes place between an off position in which the safety belt is raised away from the body of the passenger and a restraining position which brings the safety belt in contact with his body, roughly at the height of his shoulders. The guide, within the range of the restraining position, runs essentially vertically along a door post. There is also provided a locking mechanism that, when the belt is in the restraining position, secures the articulation member against undesired sliding, thus assuring that the belt articulation member stays in the restraining position and safely transmits the forces acting on the belt to the vehicle frame, even if the vehicle overturns. This locking mechanisms consists essentially of a lock bolt on the frame that is controlled by a vacuum actuated control unit. When the belt articulation member slides into the restraining position, this bolt is operated by the control unit so as to engage in a through hole provided in the member. However, the vacuum-actuated control unit is expensive and is trouble prone.